This invention relates to a heat generator, typically employed in automobiles, the generator having an operating chamber defined in a housing, a rotor disposed inside the housing and driven by a shaft which is connected to some form of driving machine like the vehicle engine or an electric motor. The operating chamber contains a viscous fluid and where heat generated by the rotor rotating in the viscous fluid can be extracted from the generator by passing another fluid across the surface of the housing, typically by means of an annular passageway formed between the housing and a surrounding housing jacket through which heat extracting fluid flows. Therefore the operating chamber of the generator is the heat generating chamber containing the viscous fluid whereas the annular passageway is the heat radiating chamber through which the heat exchanging fluid such as engine coolant is arranged to pass through, and which, for instance, can be piped to the passenger compartment of an automobile.
Furthermore, generators may also be applied to interface directly with the surrounding fluid contained in a reservoir. In this case, no jacket is required as the housing is at least partially submerged in the reservoir fluid, and heat is directly conducted from the housing by the surrounding fluid in the reservoir.
Of the many types of heat generators known, a typical example is shown in U.S. Pat. No. 6,129,287. Here a rotor element is formed to include a tubular portion which serves as a storage chamber for the viscous fluid and where an solenoid-operated actuator mounted on the generator used to regulate the amount of viscous fluid arriving or departing the storage chamber. Hydraulic systems with flow control devices operating without fluid filtration have been know to be troubled by fluid borne contamination, especially when surfaces become scoured should abrasive material reach in-between the sliding surfaces, causing leakage. By contract, U.S. Pat. No. 6,152,084 discloses an alternative form of heat generator where no provision is made for regulating the amount of viscous fluid held by the heat generating chamber, as here the chamber remains at 50% to 70% full of fluid. The chamber is largely occupied by a rotor having the form of a flat disc positioned between respective faces of a surrounding housing. During operation, as the viscous fluid held by the heat generating chamber heats up, the expanding volume of viscous fluid takes up an increasing portion of the initial 30% to 50% dead space volume. As a consequence, some interior space is wasted due to there being provision for an air or inert gas pocket and as a result, and performance during operation may be lower than with the earlier type described in U.S. Pat. No. 6,152,084 due to the mixing of the gas with the viscous fluid during operation.
There is a need for a new solution for an improved heat generator whereby the working pressures existing within the heat generating chamber can be used with good effect to allow in the adjustment of the volume amount of viscous held in fluid heat generating chamber, depending on operating conditions. The chances of external leaking of fluid into the environment due to expanding volume of fluid should be avoided whenever possible
The present invention seeks to alleviate or overcome some or all of the above mentioned disadvantages of earlier machines, in a device that is simple to build, comprising few working parts and having preferably cavitational as well as fluid shearing characteristics for generating heat in the viscous liquid.